Method and apparatus for drying



June 20, 1950 w. N. FRYE 2,511,339

METHOD AND APPARATUS FOR DRYING TEXTILE MATERIALS BY HIGH-FREQUENCY ELECTRIC FIELDS Filed on. 1, 1945 s Sheets-$heet 1 1 HIGH fRf/Jl/[A/CY 5 27 37 J2 nal/470R 54 61 faz /H/// 1; ea 32 33 Has 391:]

HIGH 552%??? 44 2 I I W1 ii HIGH Y 53555350? 6' 144 z zzz m 14%; 4 t? 21 .1" L L324! L; r 132 U 12, 1,2 lNVENTOR 1} June 20, 1950 w. N. FRYE 2,511,839

METHOD AND APPARATUS FOR DRYING TEXTILE MATERIALS BY HIGH-FREQUENCY ELECTRIC FIELDS Eiled Oct. 1, 1945 s Sheets-Sheet 2 ooo 'o'oo we 8] O o o o FREQUENCY 0 0 05011470 '/-"1.,.,., I 1 1 I 1 I 1- l l l a 83 I Elly 7 h 1 oar/11,4 70R 1 wsamr/m 156 1,2

, .3 INVENTOR W11 Mam/#5 June 20, 1950 w. N. FRYE 2,511,839

METHOD AND APPARATUS FOR DRYING TEXTILE MATERIALS BY HIGH-FREQUENCY ELECTRIC FIELDS Filed Oct. 1, 1945 3 Sheets-Sheet 3 HIE/7 FREQUENCY CUT/{1470 oooooo o ooOooocO/ 115 OOOOOOO OOOOOOC oooooocv OOOOO HIGH FREQUENCY 2 E Z 0 0501mm? INVENTOR Patented June 20, 1950 METHOD AND APPARATUS TEXTILE MATERIALS B OR DRYING HIGH-FRE- QUENCY ELECTRIC FIELDS William Nelf Frye, Petersburg, W. Va. Application October 1, 1945, Serial No. 619,718

23 Claims. 1

This invention relates to new and useful improvements in the separation of liquids from textile materials by evaporative action, 1. e., drying.

More particularly, the invention relates to a method and apparatus for drying textile fabrics, which have been laundered or dry-cleaned by solvents and subjected to the usual wringing or spinning operations, by means of radiant energy in the form of a high frequency electric field.

It has heretofore been customary to place laundry, for example, in a perforated metal drum, apply radiant energy thereto by means of gas or electric heating means, and pass a current of air therethrough. In such apparatus, the metal drum becomes very hot, and to prevent scorching or burning of the laundry, it must be removed from the drum substantially as soon as the current of air is stopped. Such devices there'- fore require close personal attention to prevent injury to the laundry.

It is an object of the present invention to eliminate the above-mentioned difilculties by several co-acting means designed to provide excellent,

quick, safe, drying conditions, and requiring a minimum of personal attention. The co-acting means comprise, an electrically substantially non-conducting, rotary drum, means to subject the compass within the drum to a high frequency electric field, and means for passing a current of air through the drum in contact with the fabric to carry away the evolved vapors; and the sub-combinations thereof.

It is a further object of this invention to provide a quick, safe method and apparatus for drying clothes and other textile materials that have been cleaned with a solvent whose vapors form an explosive mixture with air.

Other objects of the invention will become apparent from the further description, the drawings, and the hereunto appended claims.

One of the most important improvements is to be found in my application of high frequency heating, whereby in fact, the heat is generated within the material itself, no transfer of heat is involved, and the associated apparatus is not heated appreciably, thereby preventing scorch-' ing or burning of the material.

The frequency of the high frequency current maybe, but is not necessarily, selected to give a maximum heating eifect when the material is first placed in the rotary drum. By utilizing a frequency of this nature, the power applied to the heating will gradually diminish as the drying proceeds.

Clothes and other textile materials that have been treated with a solvent whose vapors form an explosive mixture with air, may be quickly and safely dried in accordance with my invention. Such materials may be heated internally by means of the high frequency electric field to a temperature above the flash point of the solvent and a. current of relatively cool, dry air passed over the materials in sufflcient volume to reduce the temperature of the evolved vapors to a temperature below the flash point. Alternatively, the air may be in sufficient volume to prevent the formation of an explosive mixture.

The invention contemplates the use of either a high frequency electrostatic field, or the use of a high frequency electromagnetic field. With respect to the electrostatic field, a heating effect is obtained regardless of whether the liquidwet textile fabric is an electrical conductor or an imperfect dielectric (non-conductor). With respect to the electromagnetic field, however, the liquid-wet textile material should be sufficiently electrically conductive that the high voltage, high frequency electromagnetic field will set up eddy currents therein. The absorption heating of imperfect dielectrics by an electromagnetic field is relatively small.

Tests have shown that the electrical conductivity of cloth varies from substantially zero, when dry, to a relatively high value at 50% moisture saturation, and above. Thus, textile fabrics containing sufilcient moisture, such as laundry, for example only, may be dried by either the electrostatic or the electromagnetic high frequency field. Also, woolen and other textiles containing sufllcient moisture, may be dried with either high frequency field.

Also, textile materials which have been treated with electrically conductive liquids other than water, may be dried with either the electrostatic or the electromagnetic field.

In the drawings forming a part of this disclosure, in which like numerals are used to designate similar parts, several embodiments of the invention have been chosen for illustration, more or less diagrammatically, and in the drawings:

Figure 1 is a sectional view of a batch type drying pparatus in accordance with the present invention, utilizing ring electrodes, taken along the line l| of Fig. 2,

Figure 2 is a sectional view taken along the line 2-4 of Figure 1, I

Figure 3 is a horizontal sectional view of an insulating member showing a modified arrange- 3 ment of the high frequency current receiving ring electrodes,

Figure 4 is a transverse sectional view of the insulating member showing another arrangement and form of electrodes.

Figure 5 is a top plan view of the rotary drum illustrated in Figure 1, showing a further modified form of high frequency electric field generating means,

Figure 6 is a horizontal sectional view of the insulating member illustrating a modified arrangement of the high frequency electric field generating means illustrated in Figure 5,

Figure 7 is a sectional view taken along the line 1-1 of Figure 8, illustrating a modified form of drum and a further modification of the high frequency electric field generating means,

Figure 8 is a transverse sectional view taken along the line 8-8 of Figure '7, v Figure 9 is a view illustrating diagrammatically a further modified form of high frequency electric field generating means, showing both said nieans'in top plan view,

I Figure 10 is a vertical sectional view through a continuous type drying apparatus in accordance with the present invention," and illustrating a further modification of the' ring electrodes,

Figure 11 is a detail view illustrating the manher in which the upper electrode of Figure '7, slightly modified, may be supported with respect to the drum in Figure 10,

Figure 12 is a detail view taken along the line 82-42 of Figure ii, and

Figure 13 is a diagrammatical view similar to Figure 9, illustrating a slightly modified form of the high frequency electric field generating means illustrated therein, which is adapted to be used in the apparatus illustrated in Figure 10.

Referring to Figures 1 and 2, there is illustrated a casing i having a top wall 2, a bottom wall 3, a rear wall 4, a front wall 5, and side walls 6 and l. A vertical partition 8 divides the casing i into iwvo compartments. The casing i has an air inlet opening 9 controlled by a sliding valve it, and an air outlet ii controlled by a sliding valve l2.

A tumbler or drum it of cantilever construction having perforations it and baiiies i5, is rotatably supported in the casing l, by means of a bearing l6 mounted on the partition ii through which a shaft ill which is connected to the drum it extends. Also supporting the drum are, as illustrated, a bearing l5 supported by the front wall 5 into which a tubular member it which is connected to the drum it extends, and rollers it and ill preferably constructed of an insulating material and supported for rotation on transverse members 22 and 23, which are in turn supported on longitudinally extending angle member 24 and 25. Riding rings 2% and 2?, preferably constructed of the same material as the drum and suitably attached thereto, as by polymerization, form trackways for the rollers 2d and -2i. The members 24 and 25 are suitably attached to the walls l and 6, respectively. It is to be understood that the rollers 2@ and/or 2!, and/or the bearing i5 may be omitted in drums designed to carry only a small load.

The drum i3 is constructed of-"arly suitable material which is electrically substantially nonconducting. Preferably, the drum'is 'constructed of a synthetic resin such as a molded phenolic condensation product, or certain of the ureaformaldehyde, vinyl or acrylic resins. As illustrated, the drum is -formed of a two piece construction. The shaft ii, the main body 2d and the lifting baflles iii are molded in one piece. The open end of the drum is partially closed by a slightly inwardly curved annular member 29 having the outwardly extending tubular portion 19,- and this is also, as illustrated, molded in one piece. The member 29 fits inside of the drum and is fastened in any suitable manner, as by polymerization, to the drum and also the baffles. An opening 36 in the front wall of the casing provides an access means to the drum. The opening 30 may be closed by a door 8i.

In the preferred embodiments of my invention, an insulatin member surrounds the drum. In Figures 1 and 2, a tubular, cylindrical heat insulating member 32 surrounds and is slightly spaced from the drum H3. The member 32 may be formed of one of the above-noted resins, or it may be formed of a ceramic material, etc., is electrically non-conducting and is supported by suitably recessed members 33 and 36 which are attached to the walls 5 and 8 of the casing, respectively. Similar members 35 and 36 may be placed adjacent the top of the insulating member to hold it in position. Openings 3i and 38 are provided in the top and bottom portions respectively of the insulating member. Also suitable openings 39, Figure 3, are provided to permit the rollers 20 and 2| to extend therethrough to contact the riding rings 25 and 27. Extending upwardly from adjacent the bottom of the casin i to the bottom opening 38 in the insulating member is a duct Gil. Preferably, the upper end of the duct it is provided with a rubber sealing means M. A duct 32 connects the duct (it to a blower 13 supported adjacent the bottom of the casing. The blower 413 discharges through the air outlet opening ii.

The blower 63 is direct-connected to a motor 66 by means of a shaft 65 extending outwardly from one side of the motor through an opening in the wall 8. Extending outwardly from the other side of the motor is a driving pulley at. The pulley 16 drives the drum i 3 through a speed reducing pulley assembly comprising a large pulley (l7 and a small pulley 63. The pulleys ii and it are suitably keyed to a shaft 39 which is rotatably supported by the members 56 and 5G. The pulley i? is driven by a belt 5i which passes around it and the driving pulley it. A pulley 52 is keyed to the shaft H and is rotated by means of a belt 53 connected to the small pulley l8. Obviously, the drum and blower may be driven by separate motors if desired, and the motor driving the blower may be a variable speed type.

A high frequency electric current receiving member in the form of a ring electrode ti l encircles and is supported adjacent the Open and of the drum i 3 and a similar high frequency electric current receiving member in the form of a ring electrode 55 encircles and is supported adjacent the opposite end of the drum. The rin electrodes 56 and 55 may be secured to the drum by means of stud bolts 55 (Figure 1). Brush means 57 electrically connect the electrode members 5d and 55 by means of suitable conductors Eli and 6! to a high frequency oscillator or gen- 35 and the high frequency oscillator 62 are energized by switch means in the' iis'ual manner. The textile materials are subject'edfto the high frequency electrostatic field setup within the com- 5. pass of the drum l3 between the electrodes I4 and 55, and are heated thereby as they are tumbled by the lifting means l5. The blower draws in air through the inlet opening 8, the top opening 31 in the insulating member 82, thence through the perforations H into and out of the drum 13' to the duct 40 and the blower 48 where it is discharged to the atmosphere through the outlet I l. A portion of the air circulating through the casing passes around the outside of the drum I3, between the drum and the insulating member 32. This latter current of air readily removes any vapors passing out through the openings, l4, and also, it serves to cool the electrode members 54 and 55. The current of air passing through the drum I3, passes over and through the textile materials therein, picking up the evolved vapors for discharge from the apparatus. When the material is dried to the desired extent, the motor 44 and oscillator 62 are deenergized, and the material removed from the drum I3.

In the modification illustrated in Figure 3, stationary high frequency electric current receiving ring electrode members 66 and 81 are supported in encircling relation to said drum. In this modification, however, the ring electrodes are suitably secured to and supported in the insulating member 32 rather than on the drum l3. The said members 66 and 61 are connected to the high frequency oscillator 62 by means of suitable conductors 60 and GI. The operation is otherwise the same as that given above in connection with Figures 1 and 2.

In the modification illustrated in Figure 4, stationary high frequency electric current receiving plate electrode members 68 and 68 are suitably secured to and supported in the stationary insulating member 32 in diametrically opposed relation, offset slightly from a vertical center line through the drum, in the direction of rotation of the drum. The members 68 and 68 are substantially equal in length to the length of the drum, and are connected to the high frequency oscillator 62 by means of suitable conductors 58 and 6!. The operation is otherwise the same as that given above in connection with Figures 1 and 2.

In the modification illustrated in Figure 5, the high frequency electric field generating means comprises a high frequency electric current receiving member in the form of a coil in surrounding or encircling the drum l3 and suitably secured thereto by strap means II formed of insulating material, or other suitable means. The coil 18 is electrically connected to a pair of slip rings 12 and 13 either directly, or by conductors or wires 12' and 13'. The slip rings 12 and 13 are contacted-by the brush means 51 which are in turn electrically connected to the oscillator 52 by conductors 50 and iii. The slip rings 12 and 13 may be secured to the drum H by means of cars 14 having eyelets therein through which stud bolts 56, preferably of insulating material, may extend.

In the modification illustrated in Figure 6, the high frequency electric current receiving member comprises a coil 15 stationarily secured to and supported by the heat insulating member 32 to surround or encircle the drum l3. The coil 15 is electrically connected to the high frequency oscillator 62 by suitable conductors 68 and The operation of the device illustrated in Figure 5, or Figure 6, is substantially the same as the operation set forth above in connection with are preferably limited to those having sumcient' conductivity to permit eddy-currents to be generated therein by means of the high frequencyelectromagnetic field.

In the modification illustrated in Figures 7 and 8, the drum I8 diflers from the drum l3 only in the end member 11. The member 11 takes the form of a slightly inwardly curved, annular ring which is suitably secured to the drum and battles I5. This construction provides a larger opening to the drum. A tubular member I8 surrounds the opening 88 in the casing i and is suitably secured to the wall 5 by angle brackets 18. A high frequency electric current receiving plate electrode member is suitably supported by some of the brackets 18 on the tubular member 18 and extends inwardly to adjacent the rear, slightly inwardly curved, or convex wall 8| of the drum. The electrode 80 is preferably placed or embedded in an insulating material 82 such as a synthetic resin. A second high frequency electric current receiving plate electrode member 83 is supported in the insulating member 82 in diametrically opposed relation to the electrode member 80. v

The electrode members 80 and 83 are connected to the high frequency oscillator 62 by suitable conductors 60 and Si, and are preferably offset slightly from a vertical center line through the drum, in the direction of rotation of the drum. The operation of the device illustrated in Figures 7 and 8 is the same as that given above in connection with the device illustrated in Figures 1 and 2.

Only one riding ring 28 is illustrated in Figure 7 and this is positioned adjacent the inlet end of the drum. It is to be understood, however, that more than one roller supporting means may be used 'if desired.

With respect to the manner of securing the high frequency electric current receiving members to the insulating member 32, in Figures 3, 4, 6 and 8, as illustrated, the current receiving members are placed in the mold, and the insulating member is molded with the electrodes in position, suitable provisions being made for differences in the coeillcients of expansion of the two materials. This articular construction is not necessary, however, since it is obvious that the electrode and coil members may be secured to the insulating member 32 in other ways, and further, the electrode and coil members do not have to be positioned in recesses, as illustrated in the above noted figures. Members such as 68 and 68, for example, may be secured to the insulating member by stud bolts such as 56. Coil member 15, for example, may be secured to the insulating member by straps such as H A modified form of high frequency electnic current receiving members is somewhat diagrammatically illustrated in Figure 9. In this figure, which illustrates both members in top plan view, the members comprise coils 84 and 85 suitably mounted or embedded in an insulating material 85 and 81. The member 84 is adapted to be supported in the drum illustrated in Figure 7 in exactly the same manner in which the electrode 80 is supported. The member 85 is adapted to be supported in the heat insulating member 32 as the plate electrode 83. The operation is the same as reviously described in connection with Figures 1 and 2.

In the modification illustrated in Figure 10, a continuous type of drying drum is illustrated.

7. This apparatuscomprises a casing "I having a top wall I02, an inclined base I03, a rear wall I04 and a front wall I05. The inclined base I03 functions to incline the drum downwardly from the material inlet end to the material outlet end when it is supported on a substantially horizontal supporting member, whereby the material is caused to pass continuously therethrough.

The drum II: is provided with suitable lifting baflies II 5, preferably molded integral therewith, and riding rings 826 and IN which are secured thereto in any suitable manner, as by polymerization. The drum H3 is rotatably supported by the rollers I20 and I2I supported on transverse members E22 and I23, respectively. These roller means and their supporting means are substantially the same as the similar means illustrated in Figures 1 and 2. Preferably, guiding rollers 220 and TM are provided adjacent the top portion of the drum. These rollers are supported by transverse members 222 and 223 which are in turn secured to longitudinal members 224, which are in turn secured to the casinglbl. A motor Md is supported on the top wall N2 of the casing and rotates the drum by means of a pulley Hit and belts I53 which pass around the pulley M and a ring pulley 25G uitably secured to the drum M3.

The front wall I05 of the casing is provided with an air outlet opening iii. A blower Hi3 communicates with the air outlet opening ill by means of a duct M2. The wall it? is also provided with access means to the drum in the form of an opening use having a chute Zllli suitably supported therein. A conveyor 2m may be used to feed material to the chute for delivery into the drum M3. The end wall Hit of the casing is provided with access means to the drum in the form of an opening lad through which the material is discharged by means or a. conveyor 282 which extends into the casing therethrough. The opening I30 also provides, in the modification chosen for illustration, an air inlet to the casing and drum.

iwo pairs or ring electrodes I 5i, i522 and Hal, I52" encircle and are secured to the outer surface of the drum IIll by stud bolts E58. High frequency current is supplied to these electrodes by brush means such as the brush means 51 illustrated in Figure 2. As illustrated diagrammatically, the electrodes W2 and it? are electrically connected to one side of the high frequency oscillator Hi2 by wires Hi8, i158 and IE8. Electrodes lot and B55 are electrically connected to the other side of the high frequency oscillator it? by means of wires H9, 659' and tilt.

An insulating member i 32, similar to'the member 32 above described, surrounds and is spaced from the drum H3. The insulating member lad is supported by suitably recessed members i323 and I34 which are attached to a partition wall M8, spaced inwardly from the wall Mid, and provided with a suitable opening through which the drum H3 extends, and the wall 35. Similar members I35 and I36 may be placed adjacent the top of the insulating member to hold it in position.

The drum H3 is preferably provided with perforations M4 to permit the vapors to readily escape from the vicinity of the material. The blower I43 draws a current of air through the opening I30 into and through the drum lie to the outlet duct I42. A portion of the air drawn in by the fan passes over the exterior surface of the drum, serves to cool the electrodes ltd,

I5 I I52 and H52, and readily removes the vapors passing out through the openings M4. A tubular member 203, preferably substantially semi-cir= cular in cross section (Figure '12), surrounds the air outlet opening Ill and is suitably supported by the wall I05 as by brackets no. The tubular member 268 extends a short distance into the drum H3 and functions to reduce the quantity of air which would otherwise be drawn over the outer surface of the drum.

Figure ll illustrates the manner in which the high frequency electric field generating means illustrated in Figures 7 and 8 may be applied to the continuous drum illustrated in Figure 10. A high frequency electric current receiving plate electrode member ltd having a length substantially as long as the drum and preferably embedded in a suitable member of insulating material H82, which extends beyond each end of the plate electrode, may be supported on the tubular member 203 as by the brackets 2 It, and on a suitable angle bracket 2&5 as by brackets 2i i The angle bracket 2% is secured in any suitable manner to the wall it 'i as by bolts 2%. TheJcooperating plate electrode, of substantially the same length as the drum, may be supported in the heat irmulating member H32 in the same manner andposition as the electrode 83 as illustrated in Figures 7 and 8.

Figure 13 illustrates somewhat diagrammatically a high frequency electromagnetic field gen erating means for the continuous drum type of apparatus in which the high frequency electric current receiving members consist of coils i5 1 and its embedded in suitable members of insulating material 0% and 98?. The member I85 is supported on the tubular member 203 and the angle bracket 28%; in the same manner that the member i532 is supported as illustrated in Figure 11. The member i877 may be supported on the heat insulating member in the same manner and position that the plate electrode 83 is supported, as illustrated in Figures 7 and 8.

With respect to the coils 8d and 85, Figure 9, and coils i8 3 and W5, Figure 13, either the upper or the lower coil member may be omitted where the power requirements are small.

The apparatus disclosed in Figure 10 may be provided, in lieu of the two pairs of ring electrodes illustrated, with only one pair of ring electrodes as illustrated in Figure 1 if the drum is short. For very long drums, more than two pairs of the electrodes may be desirable. Also, the high frequency electric field generating means illustrated in Figure 10 may be replaced by one or more pairs of ring electrodes supported in the insuating member 832 in the manner illustrated in Figure 3; or by means of a high frequency coil surrounding or encircling the drum as illustrated in Figure 5, or Figure 6; or plate electrodes such as 8% and d9 of figure 4 extending the full length of the drum, and supported by the heat atmospheric air or other gas drawn through and around the drum by the blower 3, picks up the evolved vapors for discharge from the ap-. paratus. Obviously, the length and angle of inclination of the drum should be so correlated that the material is dried to the desired extent when it is discharged therefrom.

The amount of air passing over the material in all of the modifications described herein, when treating laundry and other materials in which the evolved vapors do not form an explosive mixture with air, need not be very large. For highest efflciency, it should be just suilicient to carry away the evolved vapors as rapidly as they are formed.

In treating materials such as clothes that have been dry cleaned with a solvent whose vapors form an explosive mixture with air, as pointed out above, the materials may be heated internally to a temperature above the flash point of the solvent and a current of relatively cool air having a temperature below the flash point of the solvent passed over the materials in suflicient volume to reduce the temperatureof the evolved vapors to a temperature below'the flash point of the solvent. Alternatively, the air may ,be in sufficient volume to prevent the formation of an explosive mixture of air and solvent vapor. Also, in treating materials wet withthis type of solvent, it may be preferable to utilize the stationary type of high frequency electric field generating means disclosed, forthe reason that there might be a spark at the brush means 51 which could cause an explosion if an explosive mixture of air and solvent vapor were present. The latter is not necessary, however, if the flow of air is sufficient to meet the condition set forth above.

Inert gas, such as nitrogen, suitably cleaned combustion products, and other inert gase may be used instead of air, if desired. Ordinary atmospheric air, however, is more economical, and for this reason is preferred.

With respect to the continuous type of drying apparatus illustrated in Figure 10, it may in certain instances be desirable to supply heat to and dry the material in the material inlet end portion of the drum, as, for example, by omitting the electrodes Hi and I52. Then, the countercurrent flow of air selected for illustration in this figure, may be utilized to cool and aerate the material as it passes through the material outlet portion of the drum.

Except to cool the material as described in the preceding paragraph, the flow of air or gas relative to the movement of the material may be in any desired direction.

It is obvious that the apparatu disclosed herein may be used for drying materials other than textile materials. With obvious modifications, if any are necessary, granular materials, foods, coffee beans and other materials which may be dried in rotary drums, may be dried in apparatus constructed in accordance with the teaching of this invention.

In the above description, I have set forthseveral of the preferred embodiments'of my invention, but it is to be understood that these are given by way of illustration, and not in limitation thereof.

a,s11,esa

v.10 I claim: a v

1. In a method of drying textile materials, the steps comprising. liftin and dropp n said textile materials in an electrically substantially nonconductive rotary drum, and simultaneously subjecting said materials to a high frequency electric field while removing vapors from said drum.

2. A method of drying textile materials which comprises, lifting and dropping said textile materials in an electrically substantially non-conducting rotary drum While subjecting said materials to a high frequency electric field, and almultaneously passing a current of air over said materials.

K said materials.

4. A method of drying textile materials which comprises, lifting and dropping said textile materials in an electrically substantially non-conducting drum while subjecting said textile materials to a high frequency electrostatic field, and simultaneously passing a current of air over said materials.

5. A method of drying textile materials containing a solvent whose vapors form an explosive mixture with air, which comprises lifting and dropping said textile materials, simultaneously heating said textile materials internally to a temperature above the flash point of the solvent contained therein by direct application of a high frequency electric field, and simultaneously passing a current of air over said textile materials, the temperature of said air being cool relative to the temperature of the heated textile materials;

6. A method of drying textile materials containing a solvent whose vapors form an explosive mixture with air, which comprises heating said textile materials internally to a temperature above the flash point of thesolvent contained therein by'direct application of a high frequency electric field, and simultaneously passing a current of air over said textile materials, the temperature of said air being cool relative to the temperature of the heated textile materials.

'7. A method of drying textile materials containing a solvent whose vapors form an explosive mixture with air, which comprises subjecting said textile materials to a high frequency electric field to heat the same internally to a temperature above the flash point of the solvent contained therein, and simultaneously passing a current of air over said textile materials the temperature of said air being below the flash point of said solvent and of sufficient volume to reduce the temperature of the evolved solvent vapors to a degree below the flash point of the said solvent.

8. An apparatus for drying textile materials comprising, in combination, an electrically substantially non-conducting rotary drum for tumbling said materials, material lifting means in said drum, means for subjecting said materials in said drum to a high frequency electric field, and means for passing a current of air over said materials in said drum.

9. The combination set forth in claim 8, wherein the high frequency field is an electrostatic 10. The combination set forth in claim 8,

11. An apparatus for drying textile materials comprising, in combination, a casing having an air inlet opening and an air outlet opening, a perforated, electrically substantially non-conducting drum rotatably mounted in said casin said drum being adapted to receive therein said materials, said casing having access means to the interior of said drum, material lifting means in said drum, means for rotating said drum, means for subjecting said materials in said drum to a high frequency electric field, and means for passing a current of air through said casing and said drum.

12. An apparatus for drying materials comprising, in combination, a casing having an air inlet and an air outlet, an internal, perforated, electrically substantially non-conducting drum rotatably mounted in said casing, means for passing a current of air through said drum, and high frequency electric field generating means comprising high frequency electric current receiving member means supported in encircling relation to said drum.

13. The combination set forth in claim 12, wherein the high frequency electric current receiving member means comprises a coil.

14. The combination set forth in claim 12, wherein the high frequency electric current receiving member means comprise a plurality of ring electrodes.

ing, in combination, a casing having an air inlet and an air outlet, an electrically substantially non-conducting drum rotatably mounted in said casing, material lifting means in said drum, high frequency electric field generating means including a member supported internally of and adjacent the top of said drum in spaced relation thereto, and a substantially diametrically opposed member supported externally of and adjacent the bottom of said drum; and means for passing a current of air through said drum.

16. An apparatus for drying materials comprising, in combination, a casing having an air inlet and an air outlet, an electrically substantially non-conducting drum rotatably mounted in said casing, high frequency electric field generating means comprising a high frequency electric current receiving member supported externally of and adjacent the bottom of said drum, and means for passing a current of air through said drum.

17. In an apparatus for drying materials, the combination comprising an electrically substantially non-conducting, rotatably supported drum, means for removing vapors from said drum, high frequency electric field generating means comprising a plurality of ring electrodes, and means supporting said ring electrodes in encircling relation to said drum.

18. In an apparatus for drying materials, the combination comprising, a perforate, electrically substantially non-conducting, rotatably sup-. ported drum, material lifting means in said drum,

high frequency electric field generating means including a member supported internally of and tion thereto, and a substantially diametrically 30 15. An apparatus for drying materials comprisl2 opposed member supported externally of and adjacent the bottom of said 19. In an apparatus for mamrials, the combination comprising, an electrically substantially non-conducting, rotatably supported drum, material lifting means in said drum, and a high frequency electric field generating means comprising a high frequency current receiving member supported internally of and adjacent the top of said drum in spaced relation thereto.

20. In an apparatus for drying materials, the combination comprising, an electrically substantially non-conducting, rotatably supported drum, and a high frequency electric field generating means comprising a high frequency current receiving member including a. coil, means for supporting said member externally of and adjacent the bottom of said drum, and means for passing a current of air through said drum.

21. An apparatus fordrying material comprising, in combination, a perforated, electrically substantially non-conducting rotary drum, material lifting means in said drum, means for rotating said drum, and means for subjecting said materials in said drum to a high frequency electric field.

22. The combination set forth in claim 8, wherein the means for subjecting said materials in said drum to a high frequency electric field comprises a plurality of plate electrodes.

23. The combination set forth in. claim 8, wherein the means for subjecting said materials in said drum to a high frequency electric field comprises high frequency current receiving member means each including a coil.

REFERENCES Cll'lllED The following references are of record in the file of this patent:

UNITED STATES PATENT Number Name Date 1,560,589 Andrews et al Nov. 10, 1925 1,701,156 Heritage Feb. 5, 1929 1,731,473 Naugle Oct. 15, 1929 1,998,332 Page Apr. 16, 1935 2,042,145 Darrah May 26, 1936 2,045,381 Elberty, Jr June 23, 1936 2,1i2,0 i2 Bowdoin et al Dec. 27, 1938 2,226,871 Nicholas Dec. 31, 1940 2231557 tephen Feb. 11, 1941 2,394,754 Vang Mar. 21, 1994 2,348,115 Downes May 2, 194.4 2,366,347 Millson Jan. 2, 1945 2,406,494 Ferris Aug. 27, 1946 2,419,875 Birdseye Apr. 29, 1947 FOREIGN PATENTS Number Country Date 517,798 Great Britain Feb. 8, 1940 682,375 Germany Oct., 13, 1939 OTHER REFERENCES Electronics Brightest Star, pages 103 to 105 of the Scientific American, Sept. 1943. 

